Technical Field
The present disclosure relates to an LED light-diffusing lens for an LED street lamp which adopts an asymmetric free curved surface equation. More particularly, the present disclosure relates to an LED light-diffusing lens adopting an asymmetric free curved surface equation, in which the asymmetric free curved surface equation is applied to the LED light-diffusing lens to improve an uniformity ratio of illumination, and in particular to control an LED light source to exhibit all the functions as an LED street lamp suitable for peripheral environments and traffic lanes of a highway, and a highway LED street lamp can be placed on the market.
Background Art
Light Emitting Diodes (LEDs) are becoming more frequently employed as light sources in the industrial world including the lighting installation field for energy saving. Thus, research for effectively and efficiently using LEDs has also actively been conducted in each industrial field.
However, since an LED light source is characterized in that a rectilinearly advancing property of light is high, the light energy radiation form of the LED, which is similar to a point light source, typically takes a form of Gaussian distribution in which the light distribution concentrates to the central portion as compared to the peripheral portions, as illustrated in FIG. 1. However, this may cause a glaring phenomenon and may contribute to light pollution due to twinkling since the central light is excessively intensive as compared to the peripheral light.
Optical lenses, which are coupled to an LED side so as to diffuse and adjust the light distribution of the LED have been developed in order to remedy the disadvantages of the glaring phenomenon and the light pollution caused by the central concentration of the light.
Most LED light-diffusing lenses can perform light-adjustment to convert the LED as a point light source into a plane light source through the light diffusion. However, the radiation form of the LED subjected to the light adjustment takes a form of Lambertian distribution, as illustrated in FIG. 2, in which the central light still intensively acts as compared to the peripheral light. Thus, even brightness cannot be derived, and, as a result, the existing LED light-diffusing lenses are unsatisfactory for light diffusion adjustment of an LED light source.
That is, the twinkling problem due to the central concentration of light still exists so that the glaring phenomenon cannot be eliminated. Further, light adjustment efficiency is very poor. This means that there is considerable difficulty in adjusting emitted light of the LED, such as light diffusion.
Meanwhile, due to their various advantages, LEDs are variously utilized increasingly in various industrial fields for indoor lighting, outdoor lighting, backlight or the like, and the LED market is spreading.
Although light distribution adjustment suitable for use of each LED and stable optical characteristics obtained therefrom are sought after, conventionally developed and proposed light-diffusing LED optical lenses merely induce light diffusion with respect to emitted light of LEDs and perform light adjustment to induce light diffusion in any one of an X-axis direction and a Y-axis direction, regardless of characteristics of each use. Accordingly, the conventional light-diffusing LED optical lenses cannot derive the maximum illumination efficiency and energy efficiency according to an extraordinary nature for each use. In order to overcome this disadvantage, there has been research and development with great interest in illumination efficiency and energy efficiency for LED light sources.
In addition, LED lighting employing an LED as a light source is widely applied to ordinary street lamps, security lights, or tunnel lights, for example. However, highway LED lighting solutions do not exist.
Furthermore, to say nothing of currently operated highway street lamps, ordinary LED street lamps, even if they were to be applied as highway street lamps merely by changing the use thereof, may cause drivers to become tired due to a low uniformity ratio of illumination of LED lighting (a level of uniform distribution of light in a predetermined space) and may lead to unsafe driving conditions for vehicles traveling at high speed on the highways.